Base station apparatus, mobile station apparatus, mobile communication system and communication method

A base station apparatus in a mobile communication system comprised of a base station apparatus and a mobile station apparatus that performs communications by carrier aggregation for concurrently using a plurality of frequency bands configured from the base station apparatus,

• wherein the base station apparatus makes a determination whether the mobile station apparatus needs to perform Inter-Frequency Measurement, and when Inter-Frequency Measurement is needed as a result of the determination, based on the number of frequency bands used in communications with the mobile station apparatus and the number of frequency bands that the mobile station apparatus is capable of concurrently receiving, selects one of a first Inter-Frequency Measurement method without the need for providing a measurement gap to perform Inter-Frequency Measurement in one of the frequency bands, and a second Inter-Frequency Measurement method with the need for providing the measurement gap in one of the frequency bands.

A base station apparatus in a mobile communication system comprised of a base station apparatus and a mobile station apparatus that performs communications by carrier aggregation for concurrently using a plurality of different frequency bands configured from the base station apparatus,

• wherein the base station apparatus selects one of a first Inter-Frequency Measurement method without the need for providing a measurement gap to perform Inter-Frequency Measurement, and a second Inter-Frequency Measurement method with the need for providing the measurement gap, based on a mobile station apparatus capability concerning carrier aggregation of the mobile station apparatus, and a plurality of different frequency bands configured on the mobile station apparatus.

A mobile station apparatus in a mobile communication system comprised of a base station apparatus and a mobile station apparatus that performs communications by carrier aggregation for concurrently using a plurality of frequency bands configured from the base station apparatus,

• wherein the mobile station apparatus notifies the base station apparatus of a mobile station apparatus capability concerning carrier aggregation of the mobile station apparatus for the base station apparatus to select one of first Inter-Frequency Measurement without the need for providing a measurement gap to perform Inter-Frequency Measurement and second Inter-Frequency Measurement with the need for providing the measurement gap, and based on a control message received from the base station apparatus, performs one of the first Inter-Frequency Measurement and the second Inter-Frequency Measurement.